The present disclosure relates to image forming apparatuses.
In a commonly known image forming apparatus, a photosensitive drum and a development roller are located opposite to one another with a gap of a specific distance therebetween. The photosensitive drum is a cylindrical rotating member having a circumferential surface on which an electrostatic latent image is formed. The development roller is a cylindrical rotating member having a circumferential surface bearing developer, such as toner, for developing the electrostatic latent image formed on the photosensitive drum. In the image forming apparatus, a voltage of superposed direct current voltage and alternating current voltage is applied to the development roller causing charged toner to detach from the development roller to the photosensitive drum, and thereby developing the electrostatic latent image.
In the image forming apparatus, in order to improve development efficiency it is necessary to apply a sufficiently large voltage (referred to below as development bias) to the development roller in order that a sufficiently large amount of toner is supplied to the photosensitive drum. However, an excessively large development bias is problematic as explained below. That is, electric discharge may occur between the photosensitive drum and the development roller causing an artifact in the electrostatic latent image due to a change in electrical potential of the circumferential surface of the photosensitive drum. The artifact reduces quality of a resulting image formed on a sheet. Also, excessive current may flow in the photosensitive drum causing wearing of the photosensitive drum. Therefore, the development bias applied to the development roller during electrostatic latent image development is preferably as large as possible without being so large as to cause electric discharge to occur between the photosensitive drum and the development roller.
In one example, a developing device includes a leakage generating section and a leakage detecting section. In the aforementioned developing device, the leakage generating section causes leakage to occur between an image bearing member and a toner bearing member by adjusting voltage applied between the image bearing member and the toner bearing member. The leakage detecting section detects the leakage based on current flowing between the image bearing member and the toner bearing member.